Sustt: Energy transition, carbon credits, green medicine, Thailand develops sustainable finance taxonomy, meeting the Paris Agreement is not enough
The world's hydropower capacity is increasingly threatened by sedimentation
By Anja P.
What’s happening? The world will lose about a quarter of its original dam storage capacity by mid-century due to sediment build-up, a new study by the UNU Institute for Water, Environment and Health has found. Researchers analysed more than 47,000 of the world’s 60,000 large dams in 150 countries. (Reuters )
Why does this matter? Large dams and reservoirs play an important role in the provision of drinking and irrigation water, hydroelectricity production and flood control. Thus, storage losses will impact many parts of the economy, from farming to power production and water supply.
What did the study say? The study , conducted by the UN’s water think tank, analysed data from 47,403 dams for which information on initial storage capacity and date of construction was available. It found that the world’s dams have already lost between 13-19% of their capacity due to trapped sediment. By 2050, countries will lose an average of 23-28% – a capacity equivalent to the combined annual water consumption of China, India, Indonesia, France and Canada.
The Asia-Pacific region is the most heavily dammed part of the world, with China containing more than 24,000 dams. Around 23% of the region’s initial storage capacity will be lost by mid-century. Meanwhile, the Americas and Europe are forecasted to see average losses of 28%, while Africa’s capacity reduction will reach 24%.
What is sedimentation? Sediment accumulation is a common yet underestimated problem. In naturally flowing rivers, sediment is washed downstream to wetlands and coasts. Dams interrupt this flow, leading to silt build-up in reservoirs, which reduces their capacity and damages hydroelectric turbines and other components. Disrupted sediment flows also harm downstream communities and habitats as well as upstream regions by making them more prone to flooding.
What can be done? To address the issue, the UN researchers stressed the importance of long-term sediment management strategies. While dredging is expensive and only a temporary solution, sediment flushing is cheaper but comes with substantial impacts on downstream areas. Another common method is bypassing, by which downstream flows are diverted through a separate channel, reducing sedimentation by up to 80-90%.
There are other risks – Last year, the UN also warned that many mega-dams are approaching the end of their lifetime and require increasing maintenance to avoid dam failures, overtopping and leaking. Climate change-induced extreme weather events are further exacerbating the problem. More intense and frequent flooding can accelerate a dam’s ageing process and raise the risk of collapse. Moreover, intense rainfall contributes to upstream erosion and increases sedimentation.
At the same time as dams are facing substantial capacity losses, they are also coming under greater scrutiny for their environmental and social impacts . Interrupting the natural flow of rivers and nutrient-rich sediments reduces plant growth, diminishes food sources for aquatic animals and leads to habitat fragmentation. Research has found that the Itaipu dam along the border of Paraguay and Brazil, for instance, has caused a 70% reduction in biodiversity. The subsequent erosion of riverbeds and reduced fertility of land has knock-on effects for farmers and local communities, as the example of the Mekong river shows.
As a result, some regions have decided to turn to other forms of power production and return rivers to their natural state. US regulators, for example, have recently approved the removal of four dams on California’s second-largest river to restore important salmon habitat.
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Stat of the week
94% of carbon credits approved by the world's leading provider, Verra, had no benefit to the climate
A report conducted by the Guardian revealed carbon offsets approved by Verra are "largely worthless and could make global heating worse". The report scrutinises global brands’ green advertising campaigns, including those encouraging consumers to fly and buy new clothes while promising no harm to the environment. In response to prolific greenwashing, the EU has released new regulation on environmental standards, forcing all businesses with over 500 employees to disclose environment, social and governance standards .?
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Bite-sized insights
What else we're seeing this week ??
?? Green medicine – Urban dwellers who visit?green spaces , such as parks or community gardens several times a week may be less likely to use certain prescription drugs. Finnish Institute for Health and Welfare researchers examined survey responses from 16,000 randomly selected people living in Helsinki, Espoo and Vantaa. They found that visiting green spaces three to four times a week was associated with 33% lower odds of using drugs for mental health, 36% lower odds of using drugs for blood pressure and 26% lower odds of using drugs for asthma, compared to visiting once a week or less. Visiting at least five times a week appeared to reduce the need for blood pressure medication by 41%. However, the need for mental health or asthma drugs rose to 22% and 24% lower odds, respectively.
A separate?study ?published in Environmental Research also indicates that exposure to urban green spaces may cut the need for medication. The authors included 3,145 Barcelona residents aged 15-97 and found that just 4.7% met a guideline called the 3-30-300 rule that suggests people should be able to see at least three trees from their home, have 30% tree canopy in their neighbourhood and live no more than 300 metres away from a green space. Of these, 18% reported poor mental health, and 8.3% had seen a psychologist over the past year. Additionally, 9.4% had used sedatives or tranquillizers, and 8.1% had used antidepressants in the past two days.
?? Thailand develops sustainable finance taxonomy – The Bank of Thailand (BOT) and the local Securities and Exchange Commission (SEC) have launched a consultation on a pilot version of a sustainable finance taxonomy to help develop a common investment language for the country’s sustainable finance market and to facilitate the development of innovative products and services including green bonds, loans and index-linked services. Thailand’s taxonomy will use a traffic-light system where amber will be used for transition activities, red for polluting activities and green for sustainable projects.
Taxonomies can be a useful tool in steering the market and providing standards for investors to help increase the flow of capital toward green projects. A national taxonomy can also provide valuable information on climate-related risks for risk management teams within the financial sector.
Malaysia, Brazil and Columbia have also been developing taxonomies while the implementation of the UK’s taxonomy has been delayed. You can read more about these developments here .
?? Meeting the Paris Agreement is not enough – The Paris Agreement’s goal of limiting global warming to 1.5C – a target which forms the backdrop to many climate negotiations - will still put billions of dollars and people at?risk . In a 1.5C scenario,?half ?of the world's glaciers will melt, the Greenland and West Antarctic ice sheets are "likely" to?collapse ?and low-latitude coral reefs will disappear. This will have serious and far-reaching consequences for society.
Glacial melt, for example, has contributed toward 21% of sea-level rise over the past two decades and under a 1.5C warming scenario, sea-levels will have risen by a further 58cm by then end of the century. According to the IPCC Sixth Assessment , scientists expect the global average sea level to rise by 15-30cm by 2050 regardless of how quickly emissions are reduced now. Promises of net zero and low-emission technologies have proliferated in recent years, however, these findings strengthen calls that adaptation to climate change is also a necessary endeavour.
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